1. Field of the Invention
The present invention relates to a relocation detection method preferably used to detect relocation of an apparatus such as a machine tool or the like (referred to as an “apparatus” hereinafter), and a relocation detection unit.
2. Description of the Related Art
As cargoes possible to be used to develop weapons of mass destruction and the like, apparatuses with high accuracy and/or high function are strictly controlled so as not to be illegally exported. However, once an apparatus has been exported abroad, it is difficult to prevent the apparatus from being relocated to a country, to which the apparatus is not permitted to be exported, by a third party. Thus, a mechanism is provided to detect the relocation if the apparatus is relocated from the position where it is installed without permission, and prohibit the apparatus from being operated again.
To detect the relocation of the apparatus, a method has been conventionally used in which the magnitude of the vibration caused by the relocation is detected by an acceleration sensor. Further, another method has also been considered in which movement distance is obtained by performing second-order integration on the value of the acceleration sensor, and the relocation is detected if the movement amount excesses a reference value. In the following description, the operation of detecting the relocation of the apparatus is referred to as “relocation detection”.
As mechanisms for detecting the relocation of the apparatus, a method is proposed in which mechanical vibration is detected, and the apparatus can not be operated again if the detected vibration is larger than a predetermined value (see Japanese Unexamined Patent Application Publication No. 2003-35595). Further, as described in Japanese Patent No. 4173513 and Japanese Unexamined Patent Application Publication No. 2009-271855, a technique is proposed in which an angle sensor is attached to the apparatus, and the relocation is detected if the apparatus is rotated or tilted, so that the apparatus is prohibited from being operated again. Further, a technique is proposed in Japanese Unexamined Patent Application Publication No. 2008-134173 in which a sensor is provided between the apparatus and floor, and the apparatus is prohibited from being operated again when it is detected that the apparatus is lifted from the floor.